InSAR Observation of Menyuan Mw5.9 Earthquake Deformation and Deep Geometry of Regional Fault Zone

By using Sentinel-1A ascending and descending synthetic aperture radar (SAR) data, this paper extracts the high-precision interferometric SAR (InSAR) coseismic deformation of the 2016 Menyuan Mw5.9 earthquake, inverts the fault geometry and slip distribution using simplex method and nonnegative least squares method, and constructs the deep geometry model of regional fault zone. The results show that coseismic deformation of the Menyuan Mw5.9 earthquake is dominated by surface uplift, and the maximums along the line-of-sight direction of ascending and descending tracks are 5.3 cm and 7.1 cm respectively. The fault strike and dip angles are 133° and 43° respectively. The seismic slip is dominated by thrust component, mainly occurring in 6.14-12.28 km underground. The maximum slip is about 0.5 m, the average slip angle is 66.85°, and the earthquake moment is 1.0×10¹⁸ N·m (Mw5.94). The fitting residual root mean square of deformation observations is 0.36 cm. The deep geometry of the regional fault zone is characterized by flower structure, which inclines to the south-west as a whole. The Menyuan earthquake rupture is a blind fault which does not appear on the surface in the flower structure. Relevant results can provide the reference for studying regional crustal movement and deformation, active fault and earthquake preparation and occurrence.